Valve timing adjusting apparatus

ABSTRACT

A valve timing adjusting apparatus includes a housing, a vane rotor, a lock member, a resilient member, and a control unit. The housing includes a limitation groove, limitation stoppers, and a lock hole. When the lock member is received in the groove, the rotational phase is controlled within a predetermined range. When the lock member is fitted with the lock hole, the rotational phase is locked to a lock phase. The resilient member urges the lock member toward the limitation groove and the lock hole in the predetermined direction. The control unit controls a driving force that actuates the lock member in a direction opposite from the predetermined direction. The lock member has small and large diameter portions that are receivable in the lock hole.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2008-96465 filed on Apr. 2, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve timing adjusting apparatus for controlling valve timing of a valve that is opened and closed by a camshaft through torque transmitted from a crankshaft of an internal combustion engine.

2. Description of Related Art

A conventional fluid-actuated valve timing adjusting apparatus having a housing and a vane rotor is well known. The housing is rotatable synchronously with a crankshaft, and the vane rotor is rotatable synchronously with a camshaft. In general, in the fluid-actuated valve timing adjusting apparatus, the vane rotor has a vane that defines in the housing an advance chamber and a retard chamber that are arranged one after another in a circumferential direction. When working fluid is supplied to the advance chamber or the retard chamber, a rotational phase of the vane rotor relative to the housing is shifted in an advance direction or in a retard direction in order to achieve required valve timing.

JP-A-2002-357105 corresponding to US2002/0139332 describes a fluid-actuated valve timing adjusting apparatus that locks the rotational phase at an intermediate phase positioned between a full advance phase and a full retard phase such that a startability of the internal combustion engine is secured. More specifically, the apparatus of JP-A-2002-357105 includes a limitation groove and a lock hole. The limitation groove extends in a circumferential direction of the housing and has stoppers at opposite end portions of the groove. The lock hole is provided at one end portion of the limitation groove and is recessed at the bottom of the limitation groove. Then, a lock pin supported by the vane rotor is inserted into the limitation groove by a pressing force of a spring, and thereby the lock pin is engageable with each stopper of the limitation groove. Thus, the rotational phase is controlled within a predetermined range. Furthermore, under the condition, where the rotational phase is controlled within the predetermined range as above, the lock pin supported by the vane rotor is insertable further into the lock hole through the limitation groove due to the pressing force of the spring such that the lock pin is fitted into the lock hole. As a result, the rotational phase is locked to the intermediate phase.

In the apparatus of JP-A-2002-357105, a camshaft generates torque variations that alternately biases the vane rotor in the advance direction and the retard direction of the rotational phase. By limiting the rotational phase within the predetermined range, the displacement or shake of the vane rotor within the housing due to the alternate torque variations is limited. As a result, the lock pin supported by the vane rotor that is limited from unwanted shake is fitted into the lock hole, and thereby the performance of locking the rotational phase to the intermediate phase is improved.

In the apparatus of JP-A-2002-357105, it is possible to insert the lock pin into the lock hole through the limitation groove only under a condition, where the lock pin is engaged with the certain stopper on one end portion of the limitation groove positioned toward the lock hole. However, the lock pin supported by the vane rotor is movable back and forth or vibrated within the predetermined range between the certain stopper and the other stopper at opposite end portions of the limitation groove in accordance with the alternate torque variations. Thus, when the lock pin is once disengaged from the certain stopper on the one end portion of the limitation groove positioned toward the lock hole, insertion of the lock pin into the lock hole is prevented. The above failure in the insertion of the lock pin into the lock hole may deteriorate the performance of locking the rotational phase to the intermediate phase disadvantageously. Thus, improvement has been required.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus, it is an objective of the present invention to address at least one of the above disadvantages.

To achieve the objective of the present invention, there is provided a valve timing adjusting apparatus for adjusting valve timing of a valve that is opened and closed by a camshaft through torque transmission from a crankshaft of an internal combustion engine, the valve timing adjusting apparatus including a housing, a vane rotor, a lock member, a resilient member, and a control unit. The housing is rotatable synchronously with the crankshaft. The housing includes a limitation groove, which extends in a circumferential direction of the housing, and which has first and second limitation stoppers at first and second circumferential end portions, respectively, of the limitation groove. The housing includes a lock hole at the first circumferential end portion of the limitation groove. The lock hole is recessed further from the limitation groove in a predetermined direction. The vane rotor is rotatable synchronously with the camshaft. The vane rotor includes a vane that defines in the housing an advance chamber and a retard chamber that are arranged one after another in the circumferential direction. When working fluid is supplied to one of the advance chamber and the retard chamber, a rotational phase of the vane rotor is shifted relative to the housing in a corresponding one of an advance direction and a retard direction. The lock member that is supported by the vane rotor. When the lock member is received in the limitation groove and is engageable with each of the first and second limitation stoppers, the rotational phase is controlled within a predetermined range. When the lock member is received in both of the limitation groove and the lock hole and is also fitted with the lock hole, the rotational phase is locked to a lock phase positioned between a full advance phase and a full retard phase. The resilient member urges the lock member toward the limitation groove and the lock hole in the predetermined direction. The control unit is configured to control a driving force that actuates the lock member in a direction opposite from the predetermined direction. The lock member has a large-diameter portion and a small-diameter portion. The large-diameter portion has a first diameter. The small-diameter portion has a second diameter smaller than the first diameter and is provided on one side of the large-diameter portion in the predetermined direction, where a bottom surface of the lock hole is located. The large-diameter portion and the small-diameter portion are receivable in the lock hole.

To achieve the objective of the present invention, there is also provided a valve timing adjusting apparatus for adjusting valve timing of a valve that is opened and closed by a camshaft through torque transmission from a crankshaft of an internal combustion engine, the valve timing adjusting apparatus including a housing, a vane rotor, and a lock member. The housing is rotatable synchronously with the crankshaft. The housing includes a limitation groove, which extends in a circumferential direction of the housing, and which has first and second limitation stoppers at first and second circumferential end portions, respectively, of the limitation groove. The housing includes a lock hole at the first circumferential end portion of the limitation groove. The lock hole is recessed further from the limitation groove in an axial direction of the housing. The vane rotor is rotatable synchronously with the camshaft. The vane rotor includes a vane that defines in the housing an advance chamber and a retard chamber that are arranged one after another in the circumferential direction. When working fluid is supplied to one of the advance chamber and the retard chamber, a rotational phase of the vane rotor is shifted relative to the housing in a corresponding one of an advance direction and a retard direction. The lock member that is supported by the vane rotor. The lock member has a large-diameter portion and a small-diameter portion. The large-diameter portion has a first diameter. The small-diameter portion has a second diameter smaller than the first diameter and is provided on one axial side of the large-diameter portion where an axial bottom surface of the lock hole is located. The lock member is axially displaceable from an initial position to first and second positions in the axial direction. When the lock member is placed in the first position, the large-diameter portion of the lock member is displaceable circumferentially within the limitation groove between the first and second limitation stoppers such that the rotational phase is controlled within a predetermined range that is positioned between a full advance phase and a full retard phase of the vane rotor. When the lock member is placed in the second position, the large-diameter portion is fitted with the lock hole such that the rotational phase is locked to a lock phase positioned within the predetermined range.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a configuration diagram illustrating a valve timing adjusting apparatus of the first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1;

FIG. 3 is a schematic diagram for explaining torque variations that are applied to a drive unit shown in FIG. 1;

FIG. 4 is a view observed in a direction of IV-IV of FIG. 1;

FIG. 5 is a view observed in the direction of IV-IV of FIG. 1 showing an operational state different from FIG. 4;

FIG. 6 is a view observed in the direction of IV-IV of FIG. 1 showing another operational state different from FIGS. 4 and 5;

FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 1;

FIG. 8A is a schematic cross-sectional view taken along line VIIIA-VIIIA of FIG. 2 illustrating a part of the drive unit shown in FIG. 1 at a lock phase;

FIG. 8B is a schematic cross-sectional view taken along line VIIIB-VIIIB of FIG. 2 illustrating the other part of the drive unit shown in FIG. 1 at the lock phase;

FIG. 9A is a schematic cross-sectional view of the part of the drive unit illustrating an operational state different from that in FIG, 8A;

FIG. 9B is a schematic cross-sectional view of the other part of the drive unit illustrating the operational state corresponding to that in FIG. 9A;

FIGS. 10A and 10B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 9B;

FIGS. 11A and 11B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 10B;

FIGS. 12A and 12B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 11B;

FIGS. 13A and 13B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 12B;

FIGS. 14A and 14B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 13B;

FIGS. 15A and 15B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 14B;

FIGS. 16A and 16B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 15B;

FIGS. 17A and 17B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 16B;

FIGS. 18A and 18B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 8A to 17B;

FIGS. 19A and 19B are schematic cross-sectional views each illustrating a corresponding part of a drive unit of a valve timing adjusting apparatus according to the second embodiment of the present invention;

FIGS. 20A and 20B are schematic cross-sectional views each illustrating an operational state different from that in FIGS. 19A and 19B;

FIGS. 21A and 21B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 19A to 20B;

FIGS. 22A and 22B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 19A to 21B;

FIGS. 23A and 23B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 19A to 22B;

FIGS. 24A and 24B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 19A to 23B;

FIGS. 25A and 25B are schematic cross-sectional views each illustrating an operational state different from those in FIGS. 19A to 24B;

FIGS. 26A and 26B are schematic cross-sectional views each illustrating modification of the corresponding part of the drive unit shown in FIGS. 19A and 19B;

FIGS. 27A and 27B are schematic cross-sectional views each illustrating modification of the corresponding part of the drive unit shown in FIGS. 19A and 19B;

FIGS. 28A and 28B are schematic cross-sectional views each illustrating modification of the corresponding part of the drive unit shown in FIGS. 8A and 8B; and

FIGS. 29A and 29B are schematic cross-sectional views each illustrating modification of the corresponding part of the drive unit shown in FIGS. 8A and 8B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will be described with multiple embodiments with reference to accompanying drawings. In each of the embodiments, a corresponding component is indicated by the same numerals, and thereby overlapped explanation will be omitted.

First Embodiment

The first embodiment of the present invention will be described with reference to accompanying drawings. FIG. 1 is an example, in which a valve timing adjusting apparatus 1 according to the first embodiment of the present invention is applied to an internal combustion engine of a vehicle. The valve timing adjusting apparatus 1 is a fluid-actuated valve timing adjusting apparatus employing hydraulic oil serving as “working fluid” and adjusts valve timing of an intake valve serving as a “valve” that is opened and closed by a camshaft 2.

(Basic Configuration)

A basic configuration of the valve timing adjusting apparatus 1 will be detailed below. The valve timing adjusting apparatus 1 includes a drive unit 10 and a control unit 30. The drive unit 10 is actuated by hydraulic oil and is mounted on a transmission system that transmits an engine torque to the camshaft 2 from a crankshaft (not shown) of the internal combustion engine. The control unit 30 controls supply of hydraulic oil to the drive unit 10.

(Drive Unit)

As shown in FIGS. 1 and 2, the drive unit 10 includes a housing 11 and a vane rotor 14, and the housing 11 has a shoe member 12 and a sprocket member 13.

The shoe member 12 is made of metal and has a tubular portion 12 a and multiple shoes 12 b, 12 c, 12 d. The tubular portion 12 a is a hollow cylinder with a bottom or has a cup-like shape. The shoes 12 b to 12 d are arranged at the tubular portion 12 a at equal intervals one after another in a circumferential direction (rotational direction) and project radially inwardly from the tubular portion 12 a. Each of the shoes 12 b to 12 d has a radially inner surface that has an arcuate shape taken along a plane perpendicular to an rotational axis of the vane rotor 14. The radially inner surfaces of the shoes 12 b to 12 d slide on an outer peripheral surface of a hub portion 14 a of the vane rotor 14. Adjacent ones of the shoes 12 b to 12 d in the rotational direction define therebetween a receiving chamber 50.

The sprocket member 13 is made of metal and has an annular plate shape. The sprocket member 13 is coaxially fixed to an opening end of the tubular portion 12 a of the shoe member 12. A timing chain (not shown) extends and connects between the sprocket member 13 and the crankshaft. Thus, the sprocket member 13 is drivingly coupled to the crankshaft. Due to the above configuration, during the operation of the internal combustion engine, the engine torque is transmitted from the crankshaft to the sprocket member 13, and thereby the housing 11 is rotated synchronously with the crankshaft in a clockwise direction in FIG. 2.

As shown in FIGS. 1 and 2, the vane rotor 14 is made of metal and is received coaxially within the housing 11. The vane rotor 14 has opposite axial end portions that slide on a bottom wall of the tubular portion 12 a of the shoe member 12 and the sprocket member 13. The vane rotor 14 has a hub portion 14 a and multiple vanes 14 b, 14 c, 14 d. The hub portion 14 a has a column shape.

The hub portion 14 a is coaxially fixed to the camshaft 2. Due to the above configuration, the vane rotor 14 is rotatable synchronously with the camshaft 2 in the clockwise direction in FIG. 2, and is rotatable relative to the housing 11. The vanes 14 b to 14 d are arranged at the hub portion 14 a at equal intervals in the rotational direction and project radially outwardly from the hub portion 14 a. Thus, each of the vanes 14 b to 14 d is received by the corresponding receiving chamber 50. Each of the vanes 14 b to 14 d has a radially outer surface that has an arcuate shape taken by a plane perpendicular to the rotational axis of the vane rotor 14. The radially outer surfaces of the vanes 14 b to 14 d slide on an inner peripheral surface of the tubular portion 12 a.

Each of the vanes 14 b to 14 d divides the corresponding receiving chamber 50 into an advance chamber 52, 53, 54 and a retard chamber 56, 57, 58 arranged one after another in the rotational direction. In other words, the vanes 14 b to 14 d and the housing 11 define therebetween fluid chambers. Specifically, the advance chamber 52 is defined between the shoe 12 b and the vane 14 b, the advance chamber 53 is defined between the shoe 12 c and the vane 14 c, and the advance chamber 54 is defined between the shoe 12 d and the vane 14 d. Also, the retard chamber 56 is defined between the shoe 12 c and the vane 14 b, the retard chamber 57 is defined between the shoe 12 d and the vane 14 c, and the retard chamber 58 is defined between the shoe 12 b and the vane 14 d.

In the above drive unit 10, supply of hydraulic oil to the advance chambers 52 to 54 and drain of hydraulic oil from the retard chambers 56 to 58 shift a rotational phase of the vane rotor 14 relative to the housing 11 in an advance direction. Thus, valve timing is advanced accordingly. In contrast, supply of hydraulic oil to the retard chambers 56 to 58 and drain of hydraulic oil from the advance chambers 52 to 54 shift the rotational phase of the vane rotor 14 relative to the housing 11 in the retard direction. Thus, valve timing is retarded accordingly.

(Control Unit)

In the control unit 30, an advance passage 72 extends through the camshaft 2 and a bearing (not shown) that journals or pivotally supports the camshaft 2. As shown in FIG. 1, the advance passage 72 is always communicated with the advance chambers 52 to 54 regardless of the operational state of the drive unit 10. Also, a retard passage 74 extends through the camshaft 2 and the bearing that journals the camshaft 2, and the retard passage 74 is always communicated with the retard chambers 56 to 58 regardless of the operational state of the drive unit 10.

A supply passage 76 is communicated with a discharge port of a pump 4 serving as a fluid supplier. The pump 4 suctions hydraulic oil from an oil pan 5 through an inlet port of the pump 4 and discharges hydraulic oil from a discharge port of the pump 4. The pump 4 of the present embodiment is a mechanical pump driven by the crankshaft, and thereby during the operation of the internal combustion engine, hydraulic oil is continuously supplied to the supply passage 76. Also, a drain passage 78 is provided to drain hydraulic oil to the oil pan 5.

A phase control valve 80 is mechanically connected to the advance passage 72, the retard passage 74, the supply passage 76, and the drain passage 78. The phase control valve 80 has a solenoid 82 and operates based on the energization to the solenoid 82 such that the phase control valve 80 switches communication state of (a) the advance passage 72 and the retard passage 74 with (b) the supply passage 76 and the drain passage 78.

A control circuit 90 is mainly made of a microcomputer, and is electrically connected with the solenoid 82 of the phase control valve 80. The control circuit 90 controls energization to the solenoid 82 and controls the operation of the internal combustion engine.

In the above control unit 30, during the operation of the internal combustion engine, the phase control valve 80 operates based on the energization to the solenoid 82, which is controlled by the control circuit 90. Thus, the phase control valve 80 changes the communication state of (a) the advance passage 72 and the retard passage 74 relative to (b) the supply passage 76 and the drain passage 78. When the phase control valve 80 provides communication between the advance passage 72 and the supply passage 76 and communication between the retard passage 74 and the drain passage 78, hydraulic oil from the pump 4 is supplied to the advance chambers 52 to 54 through the passage 76, 72. Also, hydraulic oil in the retard chambers 56 to 58 is drained to the oil pan 5 through the passages 74, 78. As a result, valve timing is advanced accordingly. In contrast, when the phase control valve 80 provided communication between the retard passage 74 and the supply passage 76 and provides communication between the advance passage 72 and the drain passage 78, hydraulic oil from the pump 4 is supplied to the retard chambers 56 to 58 through the passages 76, 74, and hydraulic oil in the advance chambers 52 to 54 is drained to the oil pan 5 through the passages 72, 78. As a result, valve timing is retarded accordingly.

(Characteristics)

Characteristics of the valve timing adjusting apparatus 1 will be detailed below.

(Torque Variation)

During the operation of the internal combustion engine, torque variations or torque reversals are caused due to a spring reaction force of a vale spring of the intake valve that is opened and closed by the camshaft 2. The generated torque variations are applied to the vane rotor 14 of the drive unit 10 through the camshaft 2. As shown in FIG. 3. the torque variations alternately change between a negative torque and a positive torque. When the negative torque is applied to the vane rotor 14 through the camshaft 2, the rotational phase of the vane rotor 14 relative to the housing 11 is biased in the advance direction. When the positive torque is applied to the vane rotor 14 through the camshaft 2, the rotational phase is biased in the retard direction. Specifically, the torque variations of the present embodiment are likely to have a peak torque T+ of the positive torque greater than an absolute value of a peak torque T− of the negative torque due to friction between the camshaft 2 and the bearing. The torque variations have an average torque T_(ave) that biases the vane rotor 14 toward the positive torque. In other words, the average torque T_(ave) biases the rotational phase of the vane rotor 14 relative to the housing 11 in the retard direction in average.

(Biasing Torque)

As shown in FIGS. 1 and 4, the tubular portion 12 a of the shoe member 12 of the housing 11 is coaxially fixed with a housing bush 100 through a flange wall 101 of the housing bush 100. The housing bush 100 is made of metal and is a hollow cylinder. The housing bush 100 has an end portion positioned opposite from the flange wall 101 in the longitudinal direction of the housing bush 100, and the end portion defines an arcuate housing groove 102, which that extends in the rotational direction, and which is made by cutting the end portion in a radial direction.

A rotor bush 110 is made of metal and is a hollow cylinder having a bottom wall 111. The bottom wall 111 of the rotor bush 110 is coaxially fixed to the hub portion 14 a of the vane rotor 14. The rotor bush 110 has a diameter smaller than a diameter of the housing bush 100, and thereby the rotor bush 110 is coaxially received within the housing bush 100 rotatably relative to the housing bush 100. The rotor bush 110 has an end portion positioned opposite from the bottom wall 111 in the longitudinal direction of the rotor bush 110. The end portion defines an arcuate rotor groove 112, which extends in a rotational direction, and which is made by cutting the end portion in the radial direction.

A biasing member 120 is provided coaxially at a radially outer side of the housing bush 100 and is made of a metal helical torsion spring. The tubular portion 12 a of the shoe member 12 has an engagement pin 121 that is fixed thereto. The biasing member 120 has one end portion 120 a that is always engaged with the engagement pin 121 of the tubular portion 12 a. The biasing member 120 has the other end portion 120 b that passes through the housing groove 102 and the rotor groove 112 in a radially inward direction. The other end portion 120 b is loosely fitted with the housing groove 102 and the rotor groove 112.

In the present embodiment, when the rotational phase of the vane rotor 14 relative to the housing 11 is positioned between (a) a full retard phase shown in FIG. 5 and (b) a certain lock phase shown in FIG. 4, the other end portion 120 b of the biasing member 120 is engaged with an advance end of the rotor groove 112. In contrast, the other end portion 120 b of the biasing member 120 is not engaged with the housing groove 102 at the above state. During the operation of the internal combustion engine, a restoring force generated due to the twist of the biasing member 120 is applied to the rotor groove 112 of the rotor bush 110 in the advance direction against an average torque T_(ave) of the torque variations. Accordingly, the rotor bush 110 is biased in the advance direction of the rotational phase together with the vane rotor 14.

In contrast, when the rotational phase is positioned between (a) the lock phase shown in FIG. 4 and (b) a full advance phase shown in FIG. 6, the other end portion 120 b of the biasing member 120 is engaged with an advance end of the housing groove 102. Thus, the other end portion 120 b of the biasing member 120 is not engaged with the rotor groove 112 in the above state. As a result, the biasing member 120 exerts the restoring force only to the housing groove 102 of the housing bush 100. Thus, in the present embodiment, the vane rotor 14 is biased in the advance direction when the rotational phase of the vane rotor 14 is positioned on a retard side of the lock phase. However, the vane rotor 14 is not biased in the advance direction when the rotational phase of the vane rotor 14 is on an advance side of the lock phase.

It should be noted that the lock phase corresponds to a certain phase (detailed later) positioned in the intermediate phase between the full advance phase and the full retard phase. More specifically, when the rotational phase is at the certain phase, the internal combustion engine is allowed to start. Thus, when the engine is to be started, the rotational phase is set at the lock phase.

(Limitation/Lock Structure)

As shown in FIGS. 1 and 7, in the drive unit 10, a limitation guide 130 is embedded within the sprocket member 13 of the housing 11, and the limitation guide 130 is made of metal. The guide 130 has an inner peripheral surface that defines a limitation groove 132 and a lock hole 134. The limitation groove 132 opens at an inner surface 135 of the sprocket member 13 facing toward the vane rotor 14 and extends in the rotational direction of the housing 11 to have an elongated hole shape. The limitation groove 132 has opposite closed circumferential end portions 132 a, 132 b serving as “first and second circumferential end portions”, and the opposite closed end portions 132 a, 132 b are provided with limitation stoppers 136, 137 serving as “first and second limitation stoppers”. The lock hole 134 is a bottomed cylindrical hole or a cup-like hole and extends in an axial direction of the camshaft 2. The lock hole 134 opens to a bottom surface of the limitation groove 132 at the other end portion 132 b located on an advance side of the one end portion 132 a. In other words, the other end portion 132 b is located away from the one end portion 132 a in the advance direction of the rotational phase. Due to the above structure, the lock hole 134 is provided at the other end portion 132 b that is displaced from the one end portion 132 a in a direction, in which the biasing member 120 biases the vane rotor 14. Also, the lock hole 134 is recessed further from the limitation groove 132 in a predetermined direction, in which the lock pin 150 is displaced for insertion into the lock hole 134. In other words, an axial bottom surface 138 of the lock hole 134 is displaced from the bottom of the lock groove 132 in an axial direction of the housing 11 away from the inner surface 135 of the sprocket member 13, for example. In the present embodiment, the one end portion 132 a serves as a “second end portion”, and the other end portion 132 b serves as a “first end portions”.

As shown in FIGS. 1 and 2, a lock sleeve 140 that is made of metal is embedded within the vane 14 b of the vane rotor 14. The lock sleeve 140 has an inner peripheral surface that has a stepped cylindrical surface shape and that extends along the hub portion 14 a. The inner peripheral surface of the lock sleeve 140 defines a small-diameter hole 142 and a large-diameter hole 144. The small-diameter hole 142 has a diameter smaller than a diameter of the large-diameter hole 144 and is positioned away from the large-diameter hole 144 toward the sprocket member 13. The large-diameter hole 144 is always communicated with a lock passage 146 that extends through the lock sleeve 140 and the vane rotor 14.

The lock sleeve 140 of the vane 14 b supports a lock pin 150 made of metal. The lock pin 150 serves as a “lock member” and has an outer peripheral surface having a stepped cylindrical surface shape. More specifically, the stepped cylindrical surface shape or shouldered cylindrical surface shape has a large diameter portion and a small diameter portion having a diameter smaller than a diameter of the large diameter portion, and the small diameter portion is positioned on the tip end portion the stepped cylindrical surface shape. Thus, the outer peripheral surface defines a main body portion 152, a projection 154, and a force receiver 156. The main body portion 152 is coaxially received by the small-diameter hole 142 of the lock sleeve 140 such that the vane rotor 14 supports the main body portion 152 displaceably in the longitudinal direction of the lock pin 150. The projection 154 has a diameter (second diameter) smaller than a diameter (first diameter) of the main body portion 152 and projects from the main body portion 152 toward the sprocket member 13. Thus, the projection 154 serves as the tip end portion of the lock pin 150, and is provided on one axial side of the main body portion 152 where the bottom surface 138 of the lock hole 134 is located (see FIG. 8A). In the present embodiment, the projection 154 serves as a “small-diameter portion”, and the main body portion 152 serves as a “large-diameter portion” such that the projection 154 is coupled with the main body portion 152 to form the step-shaped profile. As shown in FIGS. 8A to 98, the projection 154 and the main body portion 152 have a certain radius difference δR1 measured therebetween. In other words, the certain radius difference δR1 corresponds to a difference of radiuses between the projection 154 and the main body portion 152. The projection 154 has a projection height H1 that is smaller than a depth of the limitation groove 132 and also than a depth of the lock hole 134. For example, FIG. 8A is a schematic cross-sectional view taken along line VIIIA-VIIIA of FIG. 2 illustrating a part of the drive unit shown in FIG. 1 at a lock phase. FIG. 8B is a schematic cross-sectional view taken along line VIIIB-VIIIB of FIG. 2 illustrating the other part of the drive unit shown in FIG. 1 at the lock phase. FIG. 9A is another schematic cross-sectional view of the part of the drive unit illustrating an operational state different from that in FIG. 8A. FIG. 9B is a schematic cross-sectional view of the other part of the drive unit illustrating the operational state corresponding to that in FIG. 9A. As above, in FIGS. 8A to 29B of the present specification, a pair of drawings A, B in the same figure number, such as a pair of FIGS. 10A and 10B, illustrates different cross-sectional views in the same operational state or the same rotational phase. Also, a left side in FIGS. 8A to 29B corresponds to the retard direction of the rotational phase, and a right side in FIGS. 8A to 29B corresponds to the advance direction of the rotational phase. An upward direction in FIGS. 8A to 29B corresponds to the predetermined direction, for example. Because the dimensions illustrated in FIGS. 8A to 29B are exaggerated to facilitate the clear description of the operation and advantages, the dimensions in FIGS. 8A to 29B may be different from those in the other accompanying drawings.

As shown in FIGS. 9A to 14B, in the present embodiment, the projection 154 and the main body portion 152 are configured to be insertable into the limitation groove 132 of the housing 11. In states shown in FIGS. 10A to 13B, where both the projection 154 and the main body portion 152 are inserted into the limitation groove 132 but not inside the lock hole 134, the look pin 150 is movable in the limitation groove 132, and the main body portion 152 of the lock pin 150 is engageable with one of the limitation stoppers 136, 137 of the limitation groove 132. Therefore, when the main body portion 152 is engaged with the limitation stopper 136 located on a retard side of the limitation groove 132, the rotational phase is controlled at a certain limitation phase shown in FIGS. 10A and 10B. In contrast, when the main body portion 152 is engaged with the limitation stopper 137 located on an advance side of the limitation groove 132, the rotational phase is controlled at the lock phase shown in FIGS. 13A and 13B. Because the main body portion 152 is engageable with each of the limitation stoppers 136, 137 as above, the rotational phase is controlled within a predetermined range Wp (see FIGS. 13A and 13B) between the limitation phase and the lock phase.

In contrast, in states shown in FIGS. 9A and 9B, 14A and 14B, where only the projection 154 is inserted into the limitation groove 132 but not inserted into the lock hole 134, the lock pin 150 is movable within the limitation groove 132, and it is possible to engage the projection 154 of the lock pin 150 with the limitation stoppers 136, 137 of the limitation groove 132. Therefore, when the projection 154 is engaged with the limitation stopper 136, the rotational phase is controlled to a retard-side phase that is displaced from the limitation phase in the retard direction by a dimension corresponding to the difference δR1 of the radiuses between the main body portion 152 and the projection 154 as shown in FIGS. 9A and 9B. Also, when the projection 154 is engaged with the limitation stopper 137, the rotational phase is controlled at an advance-side phase displaced from the lock phase in the advance direction by the radius difference δR1 as shown in FIGS. 14A and 148. As above, because the projection 154 is engageable with each of the limitation stoppers 136, 137, the rotational phase is controlled within a range wider than the predetermined range Wp by a dimension corresponding to twice of the radius difference δR1. In other words, the rotational phase is controlled within the range that is wider than the predetermined range Wp by a dimension corresponding to a difference of the diameters between the main body portion 152 and the projection 154.

Because the lock pin 150 has the outer peripheral surface having the step-shaped profile as above, the projection 154 or the small-diameter portion 154 at the tip end of the lock pin 150 is effectively insertable into the lock hole 134 when the lock pin 150 is engaged with the limitation stopper 137 of the limitation groove 132. Also, because of the above configuration, the projection 154 of the lock pin 150 is insertable into the lock hole 134 even when the lock pin 150 is positioned away from the limitation stopper 137 by a dimension equal to or smaller than the radius difference δR1. Due to the above, the possibility of inserting the lock pin 150 into the lock hole 134 is increased, and thereby the performance of locking the rotational phase to the lock phase is reliably increased in accordance with the difference δR1 of the radiuses between the small-diameter portion 154 and the large-diameter portion 152.

It should be noted that the limitation phase is positioned within the intermediate phase. More specifically, the limitation phase is positioned away from the lock phase in the retard direction by the predetermined range Wp. Also, the limitation phase is positioned away from the full retard phase in the advance direction by a dimension equal to or greater than the radius difference δR1.

As shown in FIGS. 8A, 8B, and 15A to 16B, in the present embodiment, the projection 154 and the main body portion 152 are configured to be insertable into the lock hole 134 of the housing 11. In a state shown in FIGS. 8A and 8B, where both of the projection 154 and the main body portion 152 are inserted into the lock hole 134, the main body portion 152 is coaxially fitted into the lock hole 134. As a result, by fitting the main body portion 152 with the lock hole 134, the rotational phase is locked to the lock phase shown in FIGS. 2A, 2B, 4A, 4B, 8A and 8B.

In contrast, in states shown in FIGS. 15A to 16B, where only the projection 154 is inserted into the lock hole 134, the lock pin 150 is movable within the lock hole 134, and the projection 154 and the main body portion 152 are engageable with the lock hole 134 and the limitation stopper 137, respectively. As a result, by engaging the projection 154 with the lock hole 134, the rotational phase is controlled to the phase that is displaced from the lock phase in the retard direction by the dimension corresponding to the radius difference δR1 as shown in FIGS. 15A and 15B. Also, by engaging the main body portion 152 with the limitation stopper 137, the rotational phase is controlled to the lock phase as shown in FIGS. 16A and 16B. As above, because the projection 154 and the main body portion 152 are engaged with the lock hole 134 and the limitation stopper 137, respectively, the rotational phase is controlled within the range that generally corresponds to the dimension of the radius difference δR1.

As shown in FIG. 1, the force receiver 156 of the lock pin 150 is coaxially received by the large-diameter hole 144 of the lock sleeve 140 such that the force receiver 156 is supported by the vane rotor 14 displaceably in the longitudinal direction of the lock pin 150. The force receiver 156 has an end surface toward the sprocket member 13, and the end surface receives pressure of hydraulic oil supplied to the large-diameter hole 144 through the lock passage 146. Due to the above configuration, there is generated a lock driving force that drives or actuates the lock pin 150 in a direction opposite from the sprocket member 13 such that the lock pin 150 is moved away from the limitation groove 132. In other words, the lock driving force actuates the lock pin 150 in a direction opposite from an insertion direction (predetermined direction), in which the lock pin 150 is displaced for insertion into the limitation groove 132 and the lock hole 134. As a result, for example, in a state, where both of the main body portion 152 and the projection 154 of the lock pin 150 are released from or disengaged from the limitation groove 132 due to the application of the lock driving force as shown in FIGS. 17A to 18B, it is possible to freely adjust the rotational phase.

In the present embodiment, the control unit 30 controls the driving force that drives the lock pin 150 in a direction opposite from the insertion direction (predetermined direction) such that the lock pin 150 is released from the lock hole 134 and the limitation groove 132 against the pressing force of the resilient member 170. Due to the above, when the rotational phase is not required to be locked, the locking of the rotational phase to the lock phase is released, and thereby the rotational phase or the valve timing is freely adjusted as required.

A lock resilient member 170 is provided inside the large-diameter hole 144 of the lock sleeve 140 between the lock pin 150 and a bottom wall of the tubular portion 12 a of the shoe member 12. The lock resilient member 170 is made of a metal compression coil spring. The lock resilient member 170 generates or stores a restoring force when the lock resilient member 170 is compressed. When the generated restoring force is applied to the lock pin 150, the lock pin 150 is pressed in the insertion direction.

Each of the positions of the lock pin 150 shown in FIGS. 17A, 18A indicates an initial position of the lock pin 150, for example. The lock pin 150 is axially displaceable in the axial direction of the housing 11 from the initial position to a first position shown in FIGS. 10A and 12A and to a second position shown in FIG. 8A, for example. When the lock pin 150 is placed in the first position, the projection 154 of the lock pin 150 is displaceable circumferentially within the limitation groove 132 between the first and second limitation stoppers 136, 137 such that the rotational phase is controlled within a predetermined range that is positioned between the full advance phase and the full retard phase of the vane rotor 14. Also, when the lock pin 150 is placed in the second position, the main body portion 152 is fitted with the lock hole 134 such that the rotational phase is locked to the lock phase positioned within the predetermined range.

(Regulation Structure)

As shown in FIGS. 1 and 7, in the drive unit 10, a regulation guide 200 that is made of metal is embedded in the sprocket member 13 of the housing 11. The guide 200 has an inner peripheral surface that defines a regulation groove 202. The regulation groove 202 opens at an inner surface 135 of the sprocket member 13 and extends in the rotational direction of the housing 11 to have an elongated hole shape. For example, the inner surface 135 faces the vane rotor 14 in the longitudinal direction. The regulation groove 202 has closed opposite end portions 202 a, 202 b. The one end portion 202 a is positioned on a side of the regulation groove 202 in the retard direction of the rotational phase and defines a limitation stopper 206.

As shown in FIGS. 1 and 2, a regulation sleeve 210 made of metal is embedded in the vane 14 c of the vane rotor 14. The regulation sleeve 210 has an inner peripheral surface having a stepped cylindrical surface shape extending along the hub portion 14 a. The inner peripheral surface of the regulation sleeve 210 defines a small-diameter hole 212 and a large-diameter hole 214. The small-diameter hole 212 has a diameter smaller than a diameter of the large-diameter hole 214 and is located away from the large-diameter hole 214 toward the sprocket member 13. The large-diameter hole 214 is always communicated with a regulation passage 216 that extends through the regulation sleeve 210 and the vane rotor 14.

A regulation pin 220 made of metal is supported by the regulation sleeve 210 of the vane 14 b. The regulation pin 220 serves as a “regulation member” and has an outer peripheral surface having a stepped cylindrical surface shape and having the step-shaped profile toward a tip end portion of the regulation pin 220. The outer peripheral surface defines a main body portion 222, a projection 224, and a force receiver 226. The main body portion 222 is coaxially received by the small-diameter hole 212 of the regulation sleeve 210 such that the main body portion 222 is supported by the vane rotor 14 displaceably in the longitudinal direction of the regulation pin 220. The projection 224 has a diameter smaller than a diameter of the main body portion 222 and projects from the main body portion 222 toward the sprocket member 13. Thus, the projection 224 serves as the tip end portion of the regulation pin 220, and the projection 224 is provided on one side of the main body portion 222, where a bottom surface 208 of the regulation groove 202 is located (see FIG. 8B). In the present embodiment, the projection 224 and the main body portion 222 have a certain radius difference δR2 as shown in FIGS. 8A and 8B. In other words, there is a certain difference δR2 of radiuses between the projection 224 and the main body portion 222. Also, the projection 224 has a projection height H2 that is smaller than a depth of the regulation groove 202.

As shown in FIGS. 8A, 8B, 11A to 16B, 18A and 18B, in the present embodiment, the projection 224 and the main body portion 222 are configured to be insertable into the regulation groove 202 of the housing 11. In state shown in FIGS. 8A, 8B, 12A to 16B, 18A and 18B, where both of the projection 224 and the main body portion 222 are inserted into the regulation groove 202, the regulation pin 220 is movable within the regulation groove 202 and the main body portion 222 is engageable with the regulation stopper 206 of the regulation groove 202. As a result, by engaging the main body portion 222 with the regulation stopper 206, the rotational phase is controlled to a certain regulation phase shown in FIGS. 12A and 12B.

Due to the above, the rotational phase is controlled within the predetermined range between the certain phase and the lock phase. In other words, the rotational phase is controlled within the range smaller than the predetermined range. As a result, the movement of the vane rotor 14 within the housing 11 is further limited, and thereby the possibility of the insertion of the lock pin 150 into the lock hole 134 is further improved. Thus, the performance of locking the rotational phase to the lock phase is effectively improved.

In contrast, in a state shown in FIGS. 11A and 118, where only the projection 224 is inserted into the regulation groove 202, the regulation pin 220 is movable within the regulation groove 202 and the projection 224 is engageable with the regulation stopper 206 of the regulation groove 202. As a result, by engaging the projection 224 with the regulation stopper 206, the rotational phase is controlled to a phase displaced from the regulation phase in the retard direction by the dimension corresponding to the radius difference δR2 as shown in FIGS. 11A and 11B.

It should be noted that the regulation phase is positioned within the intermediate phase. More specifically, the regulation phase is positioned away from the lock phase in the retard direction and is away from the limitation phase in the advance direction. In other words, the regulation phase is positioned within the predetermined range Wp.

As shown in FIG. 1, the force receiver 226 of the regulation pin 220 is coaxially received by the large-diameter hole 214 of the regulation sleeve 210 such that the force receiver 226 is supported by the vane rotor 14 displaceably in the longitudinal direction. The force receiver 226 has an end surface toward the sprocket member 13 and the end surface is applied with pressure of hydraulic oil supplied to the large-diameter hole 214 through the regulation passage 216. Due to the above, there is generated a regulation driving force that actuates the regulation pin 220 in a direction opposite from the sprocket member 13 such that the regulation pin 220 is displaced away from the regulation groove 202. In other words, the regulation driving force actuates the regulation pin 220 in a direction opposite from the insertion direction (predetermined direction), in which the regulation pin 220 is displaced for insertion into the regulation groove 202. Thereby, for example, when both the main body portion 222 and the projection 224 of the regulation pin 220 are released from or disengaged from the regulation groove 202 due to the application of the regulation driving force as shown in FIGS. 9A to 10B, 17A and 17B, the rotational phase is freely adjustable.

Due to the above, when the rotational phase is not required to be locked, the locking of the rotational phase is released, and thereby the rotational phase and the valve timing are freely adjusted as required.

A regulation resilient member 230 is provided within the large-diameter hole 214 of the regulation sleeve 210 between the regulation pin 220 and the bottom wall of the tubular portion 12 a of the shoe member 12. The regulation resilient member 230 is made of a metal compression coil spring. The regulation resilient member 230 generates a restoring force when the regulation resilient member 230 is compressed When the generated restoring force is applied to the regulation pin 220, the pin 220 is pressed in the insertion direction.

(Driving Force Control)

As shown in FIG. 1, in the control unit 30 serving as a “control unit”, an actuation passage 300 extends through the camshaft 2 and a bearing (not shown) that journals the camshaft 2. The actuation passage 300 is always communicated with the lock passage 146 and the regulation passage 216 regardless of the operational state of the drive unit 10. Also, a branch passage 302 branches from the supply passage 76 and receives hydraulic oil from the pump 4 through the supply passage 76. Further, a drain passage 304 is provided such that hydraulic oil is drained to the oil pan 5.

An actuation control valve 310 is mechanically connected with the actuation passage 300, the branch passage 302, and the drain passage 304. The actuation control valve 310 actuates based on the energization to a solenoid 312 that is electrically connected with the control circuit 90 such that the actuation control valve 310 changes the communication state between (a) the actuation passage 300 and (b) the branch passage 302 or the drain passage 304.

When the actuation control valve 310 provides communication between the branch passage 302 and the actuation passage 300, hydraulic oil from the pump 4 is supplied to each of the large-diameter holes 144, 214 of the lock sleeve 140 and the regulation sleeve 210 through the passages 76, 302, 300, 146, 216. Thus, the lock driving force that actuates the lock pin 150 is generated, and the regulation driving force that actuates the regulation pin 220 is also generated. Also, when the actuation control valve 310 provides communication between the drain passage 304 and the actuation passage 300, hydraulic oil in each of the large-diameter holes 144, 214 of the lock sleeve 140 and the regulation sleeve 210 are drained to the oil pan 5 through passages 146, 216, 300, 304. Thereby, at this time, the lock driving force that actuates the lock pin 150 is removed, and the regulation driving force that actuates the regulation pin 220 is also removed.

(Operation in the Event of Stop)

When the internal combustion engine is stopped in response to a stop command, such as a turning-off of an ignition switch, a rotational speed of the inertial rotation of the internal combustion engine decreases until the internal combustion engine completely stops, and thereby pressure of hydraulic oil from the pump 4 that is driven by the crankshaft decreases. Thus, in the drive unit 10, the force applied to the vane rotor 14 by pressure of oil supplied to the advance chambers 52 to 54 or to the retard chambers 56 to 58 is removed. As a result, when the rotational phase is positioned on a retard side of the lock phase, the restoring force generated by the biasing member 120 for biasing the vane rotor 14 is dominant. Also, in the drive unit 10, because the driving forces applied to the lock pin 150 and the regulation pin 220, respectively, are removed, the restoring forces of the resilient members 170, 230 that press the lock pin 150 and the regulation pin 220 become dominant. In the above operational condition of the drive unit 10, the rotational phase is locked to the lock phase in accordance with the rotational phase at the event of the stop command issuance.

(1) In a case, where the rotational phase at the event of the stop command issuance indicates the full retard phase shown in FIGS. 17A and 17B, the vane rotor 14 that is biased by the biasing member 120 rotates relative to the housing 11. Thus, the rotational phase is shifted in a direction, in which the biasing member 120 biases the vane rotor 14. In other words, the rotational phase is shifted in the advance direction. As a result, when the rotational phase reaches the phase displaced from the limitation phase in the retard direction by the certain amount δR1 as shown in FIGS. 9A and 9B, only the projection 154 of the lock pin 150 pressed by the lock resilient member 170 is pushed into the limitation groove 132. Furthermore, when the biasing member 120 causes the rotational phase to reach the limitation phase shown in FIGS. 10A and 10B, the lock resilient member 170 urges (presses) the lock pin 150 such that the projection 154 and the main body portion 152 are pushed into the limitation groove 132. In the present embodiment, biasing force of the biasing member 120 is applied to the vane rotor 14 only when the rotational phase is positioned on the retard side of the lock phase. As a result of the above operation and the configuration, the rotational phase is at least controlled within the predetermined range Wp.

Then, when the biasing force by the biasing member 120 causes the rotational phase to reach the phase that is displaced from the regulation phase in the retard direction by the certain amount δR2 as shown in FIGS. 11A and 11B, the regulation pin 220 pressed by the regulation resilient member 230 pushes only the projection 224 into the regulation groove 202. Further, when the biasing force of the biasing member 120 causes the rotational phase to reach the regulation phase shown in FIGS. 12A and 12B, the regulation resilient member 230 urges (presses) the regulation pin 220 such that the projection 224 and the main body portion 222 are pushed into the regulation groove 202. In the present embodiment, the biasing member 120 biases the vane rotor 14 only when the rotational phase is positioned on the retard side of the lock phase as above. As a result of the above operation and configuration, the rotational phase is controlled within a range smaller than the predetermined range Wp.

Then, when the biasing force of the biasing member 120 causes the rotational phase to reach the lock phase shown in FIGS. 13A and 13B, the main body portion 152 of the lock pin 150 is engaged with the limitation stopper 137 positioned on the advance side of the limitation groove 132. At the above state, the lock pin 150 that is biased by the biasing member 120 against the limitation stopper 137 is idealistically pressed also by the lock resilient member 170. As a result, as shown in FIGS. 8A and 8B, both of the projection 154 and the main body portion 152 are inserted into the lock hole 134 through the limitation groove 132. Due to the above insertion, the main body portion 152 that has the diameter greater than the diameter of the projection 154 is fitted with the lock hole 134, and thereby the rotational phase is reliably locked to the lock phase.

According to the present embodiment, the large-diameter portion or the main body portion 152 of the lock pin 150 is fitted with the lock hole 134. Due to the above, a fitting area or a contact area between the lock pin 150 and the lock hole 134 is greater compared with a case, where the small-diameter portion or the projection 154 of the lock pin 150 is fitted with the lock hole 134. As a result, it is made more difficult to release the lock pin 150 from the lock hole 134, and thereby the performance of locking the rotational phase to the lock phase is reliably improved.

In the present embodiment, the biasing member 120 biases the vane rotor 14 in the advance direction of the rotational phase, and the first end portion 132 b is positioned on a side of the second end portion 132 a of the limitation groove 132 in the advance direction. Due to the above, the lock pin 150, which is supported by the vane rotor 14, and which is inserted into the limitation groove 132, is pressed to the limitation stopper 137 on the first end portion 132 b of the limitation groove 132 by the application of the torque variations in the advance direction and by the biasing force of the biasing member 120, and thereby the lock pin 150 is reliably stopped by the limitation stopper 137. Thus, the lock pin 150 is reliably stopped by the limitation stopper 137 as above, and also the possibility of insertion of the lock pin 150 into the lock hole 134 is increased in a state, where the lock pin 150 is stopped by the limitation stopper 137 or even in a state, where the lock pin 150 is positioned away from the limitation stopper 137. As a result, the performance of locking the rotational phase to the lock phase is reliably improved.

However, in a case, where the internal combustion engine rotates by inertia before the engine completely stops, and also where the torque variations are applied to the vane rotor 14, the positive torque of the torque variations is applied to the vane rotor 14 in the retard direction. As a result, the lock pin 150 is displaced away from the limitation stopper 137 in the retard direction. Thus, the insertion of the main body portion 152 into the lock hole 134 may be made difficult.

Thus, in the present embodiment, the projection 154 having the diameter smaller than the diameter of the main body portion 152 is provided to the tip end portion of the lock pin 150, and the tip end portion is configured to be insertable into the lock hole 134. Thus, even when the main body portion 152 is displaced away from the limitation stopper 137 within a dimension that corresponds to the radius difference 8R1, the projection 154 is insertable into the lock hole 134 as shown in FIGS. 15A and 15B. Therefore, after the projection 154 has been inserted into the lock hole 134, the projection 154 shakes or moves within the lock hole 134 until the main body portion 152 is again engaged with the limitation stopper 137 as shown in FIG. 16. In the above, the main body portion 152 is again engaged with the limitation stopper 137 because the camshaft 2 of the internal combustion engine that rotates by inertia also exerts the negative torque to the main body portion 152 in the advance direction. As a result, the main body portion 152 that is engaged with the limitation stopper 137 is fitted into the lock hole 134 as shown in FIGS. 8A and 8B, and thereby the rotational phase is reliably locked to the lock phase.

(2) The rotational phase may be any one of phases shown in FIGS. 9A to 13B, for example, when the stop command is issued. In a case, where the rotational phase at the event of the stop command issuance corresponds to the lock phase or to a phase between the full retard phase and the lock phase shown in FIGS. 9A to 13B, the subsequent operational steps of the above case (1) are executed correspondingly from the rotational phase at the event of the stop command issuance. Therefore, also in the above case, the rotational phase is reliably locked to the lock phase.

(3) In a case, where the rotational phase at the event of the stop command issuance corresponds to the full advance phase shown in FIGS. 18A and 18B, the projection 224 and the main body portion 222 of the regulation pin 220 that is pressed by the regulation resilient member 230 is inserted into the regulation groove 202. In the above state, because the torque variations are applied to the vane rotor 14 through the camshaft 2 of the internal combustion engine that operates by inertia before the engine completely stops, the rotational phase is gradually shifted in a direction, in which the average torque T_(ave) of the torque variations is biased. In other words, the rotational phase is gradually shifted in the retard direction. As a result, as shown in FIGS. 14A and 14B, when the rotational phase reaches the phase positioned on the advance side of the lock phase by the certain amount δR1, only the projection 154 of the lock pin 150 pressed by the lock resilient member 170 is pushed into the limitation groove 132.

Further, when the rotational phase reaches the lock phase due to the biased average torque T_(ave) of the torque variations, the lock resilient member 170 presses the lock pin 150 such that the projection 154 and the main body portion 152 are inserted into the limitation groove 132 as shown in FIGS. 13A and 13B. At the above case, ideally, the projection 154 and the main body portion 152 within the limitation groove 132 are fitted into the lock hole 134 while the rotational phase remains positioned at the lock phase. Also, even when the lock pin 150 moves away from the limitation stopper 137, the projection 154 is solely inserted into the lock hole 134 firstly, and then the main body portion 152 is fitted into the lock hole 134 finally. As a result, the rotational phase is reliably locked to the lock phase.

(4) In a case, where the rotational phase at the event of the stop command issuance is positioned between the full advance phase and the lock phase, an operation similar to the operation described in the above case (3) is executed. Thus, also in the case (4), the rotational phase is reliably locked to the lock phase.

In any one of the above cases (1) to (4), because the pins 150, 220 are inserted into the grooves 132, 202, respectively, it is possible to limit the vane rotor 14 that supports the pins 150, 220 from shaking or vibrating. In the above state, because the lock pin 150 has the step-shaped profile that is reduced in diameter toward the end, the insertion of the lock pin 150 into the lock hole 134 is effectively facilitated. In other words, because the possibility of inserting the lock pin 150 into the lock hole 134 is increased, it is possible to achieve the valve timing adjusting apparatus 1 having the improved performance of locking the rotational phase to the lock phase.

(Operation at the Event of Starting)

When the internal combustion engine is started in response to a start command, such as a turning-on of the ignition switch, pressure of hydraulic oil supplied from the pump 4 remains low until the engine is capable of continuously rotating without the aid of the starter by operating the internal combustion engine under the complete combustion state. Thus, the final operational state of the engine at the previous event of stopping the engine remains. In other words, the lock resilient member 170 presses the lock pin 150 such that the lock pin 150 remains fitted into the lock hole 134. Also, the regulation resilient member 230 presses the regulation pin 220 such that the regulation pin 220 remains fitted into the limitation groove 132. As a result, it is possible to lock the rotational phase to the lock phase that allows the internal combustion engine to be started, and thereby the startability of the engine is effectively achieved.

(Normal Operation)

After the start of the internal combustion engine has been completed, pressure of hydraulic oil supplied from the pump 4 is increased. Due to the above, in the drive unit 10, the lock driving force drives the lock pin 150 against the pressing force of the lock resilient member 170 such that the lock pin 150 is released from both of the lock hole 134 and the limitation groove 132. Also, the regulation driving force drives the regulation pin 220 against the pressing force of the regulation resilient member 230 such that the regulation pin 220 is released from the regulation groove 202. Due to the above, hydraulic oil under increased pressure is supplied to the advance chambers 52 to 54 or to the retard chambers 56 to 58 in a state, where the rotational phase is allowed to be shifted. As a result, it is possible to freely adjust valve timing in accordance with the operational state of the internal combustion engine.

Second Embodiment

As shown in FIGS. 19A and 19B, the second embodiment of the present invention is modification of the first embodiment. A lock pin 1150 of the second embodiment has a main body portion 1152 and a projection 1154 that projects from the main body portion 1152. The main body portion 1152 has a chamfered part 1152 a on a side toward the projection 1154, and the chamfered part 1152 a is made by chamfering a corner portion of the main body portion 1152. The lock pin 1150 has the other chamfered part 1154 a at a tip end portion of the projection 1154, and the other chamfered part 1154 a is made by chamfering a corner portion of the tip end portion.

As a result, as shown in FIGS. 20A and 20B, when the projection 1154 is inserted into the limitation groove 132, the lock resilient member 170 presses the projection 1154 such that the chamfered part 1154 a of the tip end portion is pressed to and slides on an opening edge of the limitation groove 132. As a result, the insertion of the projection 1154 into the limitation groove 132 is smoothly executed. Also, as shown in FIGS. 21A and 21B, when the main body portion 1152 is to be inserted into the limitation groove 132, the lock resilient member 170 presses the main body portion 1152 such that the chamfered part 1152 a of the main body portion 1152 is pressed to and slides on the opening edge of the limitation groove 132. As a result, the insertion of the main body portion 1152 into the limitation groove 132 is smoothly executed. Further, as shown in FIGS. 22A and 22B, when the projection 1154 is to be inserted into the lock hole 134, the lock resilient member 170 presses the projection 1154 such that the chamfered part 1154 a of the projection 1154 is pressed to and slides on an opening edge of the lock hole 134. As a result, the insertion of the projection 1154 into the lock hole 134 is smoothly executed. Furthermore, as shown in FIGS. 23A and 23B, when the main body portion 1152 is to be inserted into the lock hole 134, the lock resilient member 170 presses the main body portion 1152 such that the chamfered part 1154 a of the main body portion 1152 is pressed to and slides on the opening edge of the lock hole 134. As a result, the insertion of the main body portion 1152 into the lock hole 134 is smoothly executed.

Similar to the lock pin 1150, a regulation pin 1220 of the second embodiment includes a main body portion 1222 and a projection 1224. The projection 1224 serves as a tip end portion that is inserted into the regulation groove 202. As shown in FIGS. 19A and 19B, the main body portion 1222 has a chamfered part 1222 a at a side of the main body portion 1222 toward the projection 1224. The chamfered part 1222 a is made by chamfering a corner portion of the main body portion 1222. Also, the regulation pin 1220 has the other chamfered part 1224 a at the tip end portion of the projection 1224, and the other chamfered part 1224 a is made by chamfering a corner portion of the tip end portion.

Thus, as shown in FIGS. 24A and 24B, when the projection 1224 is to be inserted into the regulation groove 202, the regulation resilient member 230 presses the regulation pin 1220 such that the chamfered part 1224 a of the projection 1224 is pressed to and slides on an opening edge of the regulation groove 202. As a result, the insertion of the projection 1224 into the regulation groove 202 is smoothly executed. Also, as shown in FIGS. 25A and 25B, when the main body portion 1222 is to be inserted into the regulation groove 202, the regulation resilient member 230 presses the regulation pin 1220 such that the chamfered part 1222 a of the main body portion 1222 is pressed to and slides on the opening edge of the regulation groove 202. As a result, the insertion of the main body portion 1222 into the regulation groove 202 is smoothly executed.

As above, in the second embodiment, it is possible to improve the performance of locking the rotational phase to the lock phase without damaging each of the pins 1150, 1220, each of the grooves 132, 202, and the lock hole 134.

It should be noted that in the lock pin 1150 of the second embodiment, alternatively the chamfered part 1152 a may not be provided to the main body portion 1152 as shown in FIGS. 26A and 26B. Also, alternatively, the projection 1154 may not be provided to the chamfered part 1154 a as shown in FIGS. 27A and 27B. Also, in the regulation pin 1220 of the second embodiment, the chamfered part 1222 a may not be provided to the main body portion 1222 as shown in FIGS. 26A and 26B. Also, the chamfered part 1224 a may not be provided to the projection 1224 as shown in FIGS. 27A and 27B.

Other Embodiment

Although multiple embodiments of the present invention have been described above, the interpretation of the present invention is not limited to the above described embodiments. Thus, the present invention is applicable to various embodiments provided that the embodiments do not deviate from the gist of the present invention.

Specifically, as for the lock pins 150, 1150, as shown in FIGS. 28A and 28B that shows an example of the lock pin 150, the projection 1154 may has a projection height H1 that is greater than the depth of the lock hole 134 such that the rotational phase may be alternatively locked to the lock phase by fitting the projection 1154 into the lock hole 134. Also, the regulation pins 220, 1220 may not be provided alternatively.

Alternatively, each of the limitation groove 132 and the regulation groove 202 may have a step-shaped profile that has different circumferential dimensions. More specifically, the dimension of a first part the regulation groove 202 in the rotational direction (circumferential direction) is greater than the dimension of a second part of the regulation groove 202, which is located on a side of the first part toward the bottom surface 208 as shown in FIG. 29B. In other words, the dimension of first part of the regulation groove 202 in the rotational direction is greater than the dimension of the second part in the rotational direction, and the second part is located on a side of the first part opposite from the vane rotor 14. Also, the limitation groove 132 has a first part and a second part having the circumferential dimension smaller than the circumferential dimension of the first part of the limitation groove 132. The second part of the limitation groove 132 is located on a side of the first part of the limitation groove 132 toward the bottom surface of the groove 132 as shown in FIG. 29A. Alternatively, the lock hole 134 may have a first part and a second part having a diameter smaller than a diameter of the first part, and the second part of the lock hole 134 is on a side of the first side of the lock hole 134 toward the bottom surface 138 of the lock hole 134 as shown in FIG. 29A.

The present invention may be alternatively applicable to an apparatus that adjusts valve timing of an exhaust valve serving as a “valve” and also to an apparatus that adjusts valve timing of both the intake valve and the exhaust valve.

Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described. 

1. A valve timing adjusting apparatus for adjusting valve timing of a valve that is opened and closed by a camshaft through torque transmission from a crankshaft of an internal combustion engine, the valve timing adjusting apparatus comprising: a housing that is rotatable synchronously with the crankshaft, wherein: the housing includes a limitation groove, which extends in a circumferential direction of the housing, and which has first and second limitation stoppers at first and second circumferential end portions, respectively, of the limitation groove; the housing includes a lock hole at the first circumferential end portion of the limitation groove; and the lock hole is recessed further from the limitation groove in a predetermined direction; a vane rotor that is rotatable synchronously with the camshaft, wherein: the vane rotor includes a vane that defines in the housing an advance chamber and a retard chamber that are arranged one after another in the circumferential direction; and when working fluid is supplied to one of the advance chamber and the retard chamber, a rotational phase of the vane rotor is shifted relative to the housing in a corresponding one of an advance direction and a retard direction; a lock member that is supported by the vane rotor, wherein: when the lock member is received in the limitation groove and is engageable with each of the first and second limitation stoppers, the rotational phase is controlled within a predetermined range; and when the lock member is received in both of the limitation groove and the lock hole and is also fitted with the lock hole, the rotational phase is locked to a lock phase positioned between a full advance phase and a full retard phase; a resilient member that urges the lock member toward the limitation groove and the lock hole in the predetermined direction; and a control unit configured to control a driving force that actuates the lock member in a direction opposite from the predetermined direction, wherein: the lock member has: a large-diameter portion having a first diameter; and a small-diameter portion having a second diameter smaller than the first diameter and provided on one side of the large-diameter portion in the predetermined direction, where a bottom surface of the lock hole is located; and the large-diameter portion and the small-diameter portion are receivable in the lock hole.
 2. The valve timing adjusting apparatus according to claim 1, wherein: the small-diameter portion is positioned on an end of the lock member in the predetermined direction; and the lock member has an outer peripheral surface having a step-shaped profile.
 3. The valve timing adjusting apparatus according to claim 1, wherein: the small-diameter portion has a corner in the predetermined direction; and the corner of the small-diameter portion is chamfered.
 4. The valve timing adjusting apparatus according to claim 1, wherein: the large-diameter portion of the lock member is fittable with the lock hole.
 5. The valve timing adjusting apparatus according to claim 4, wherein: the large-diameter portion has a corner in the predetermined direction; and the corner of the large-diameter portion is chamfered.
 6. The valve timing adjusting apparatus according to claim 1, further comprising: a biasing member that biases the vane rotor in one of the advance direction and the retard direction of the rotational phase, wherein the first circumferential end portion is positioned on a side of the second circumferential end portion in the one of the advance direction and the retard direction of the rotational phase.
 7. The valve timing adjusting apparatus according to claim 6, wherein: the one of the advance direction and the retard direction of the rotational phase is the advance direction; torque variations applied to the vane rotor through the camshaft bias the vane rotor in the retard direction of the rotational phase in average; and when the rotational phase is positioned on a retard side of the lock phase, the biasing member biases the vane rotor in the advance direction.
 8. The valve timing adjusting apparatus according to claim 7, wherein: the control unit removes the driving force when the internal combustion engine is stopped.
 9. The valve timing adjusting apparatus according to claim 1, wherein: the housing further includes a regulation groove, which extends in the circumferential direction, and which defines a regulation stopper at one circumferential end portion of the regulation groove; and the resilient member serves as a lock resilient member, the valve timing adjusting apparatus further comprising: a regulation member that is supported by the vane rotor, wherein the regulation member is receivable in the regulation groove and is engageable with the regulation stopper such that the rotational phase is controlled to a certain phase within the predetermined range; and a regulation resilient member that urges the regulation member toward the regulation groove in the predetermined direction, wherein: the control unit also controls a regulation driving force that drives the regulation member in the direction opposite from the predetermined direction.
 10. The valve timing adjusting apparatus according to claim 9, wherein: the regulation member has: a large-diameter portion having a first diameter; and a small-diameter portion having a second diameter smaller than the first diameter and provided on one side of the large-diameter portion where a bottom surface of the regulation groove is located; and the large-diameter portion and the small-diameter portion are receivable in the regulation groove.
 11. The valve timing adjusting apparatus according to claim 10, wherein: the small-diameter portion is provided on an end of the regulation member in the predetermined direction; and the regulation member has an outer peripheral surface having a step-shaped profile.
 12. A valve timing adjusting apparatus for adjusting valve timing of a valve that is opened and closed by a camshaft through torque transmission from a crankshaft of an internal combustion engine, the valve timing adjusting apparatus comprising: a housing that is rotatable synchronously with the crankshaft, wherein: the housing includes a limitation groove, which extends in a circumferential direction of the housing, and which has first and second limitation stoppers at first and second circumferential end portions, respectively, of the limitation groove; the housing includes a lock hole at the first circumferential end portion of the limitation groove; and the lock hole is recessed further from the limitation groove in an axial direction of the housing; a vane rotor that is rotatable synchronously with the camshaft, wherein: the vane rotor includes a vane that defines in the housing an advance chamber and a retard chamber that are arranged one after another in the circumferential direction; and when working fluid is supplied to one of the advance chamber and the retard chamber, a rotational phase of the vane rotor is shifted relative to the housing in a corresponding one of an advance direction and a retard direction; and a lock member that is supported by the vane rotor, wherein: the lock member has: a large-diameter portion having a first diameter; and a small-diameter portion having a second diameter smaller than the first diameter and provided on one axial side of the large-diameter portion where an axial bottom surface of the lock hole is located; and the lock member is axially displaceable from an initial position to first and second positions in the axial direction; when the lock member is placed in the first position, the large-diameter portion of the lock member is displaceable circumferentially within the limitation groove between the first and second limitation stoppers such that the rotational phase is controlled within a predetermined range that is positioned between a full advance phase and a full retard phase of the vane rotor; and when the lock member is placed in the second position, the large-diameter portion is fitted with the lock hole such that the rotational phase is locked to a lock phase positioned within the predetermined range.
 13. The valve timing adjusting apparatus according to claim 12, further comprising: a resilient member that urges the lock member toward the limitation groove and the lock hole in the axial direction; and a control unit configured to control a driving force that actuates the lock member in a direction away from the limitation groove and the lock hole.
 14. The valve timing adjusting apparatus according to claim 12, further comprising: a biasing member that biases the vane rotor in one of the advance direction and the retard direction of the rotational phase, wherein the first circumferential end portion is positioned on a side of the second circumferential end portion in the one of the advance direction and the retard direction of the rotational phase.
 15. The valve timing adjusting apparatus according to claim 12, further comprising: a regulation member that is supported by the vane rotor, wherein the regulation member is receivable in the regulation groove and is engageable with the regulation stopper such that the rotational phase is controlled to a certain phase within the predetermined range; and a regulation resilient member that urges the regulation member toward the regulation groove in the axial direction, wherein: the control unit also controls a regulation driving force that drives the regulation member in a direction away from the regulation groove. 